DESCRIPTION (Author's Abstract): There are currently no birth cohort, prospective studies of the impact of lead exposure on neuropsychological functioning and social adjustment in adolescence. The role of early lead exposure in adolescent neuropsychological, emotional and social development is largely unknown. Deficits in neuropsychological functioning, academic achievement, and prosocial behavior represent a serious public health problem for socioeconomically disadvantaged, inner-city youth in the United States. Early exposure to lead is believed to result in reduced intellectual attainment and learning problems. Furthermore, the link between cognitive deficits and antisocial behavior has been well established. Therefore, it is hypothesized that early lead exposure will be associated with deficits in executive function, an increase in aggressive-disruptive peer relationships, and ultimately a higher incidence/prevalence of delinquent acts. A prospective methodology will be employed to assess the long-range effects of prenatal and early postnatal lead exposure on the development of neuropsychological deficits (targeting functions known to be affected by lead as well as distinguishing populations of delinquent from non-delinquent youth), difficulties in peer relationships (utilizing innovative classroom sociometric and peer nomination methodologies), personality disturbances (utilizing standardized measures of personality and self-concept), and antisocial behavior in the home, school and community at large (utilizing parental/guardian informants and self reports). This birth cohort of approximately 300 subjects has been followed since 1980 with regularly scheduled assessments of blood lead concentration, deciduous tooth lead concentration, health history, sociohereditary factors, and neurobehavioral development.